Adapting the pinch point analysis to improve the ORC design process

Pinch point analysis can be adapted so as to assist in the early stages of designing the Organic Rankine Cycle (ORC) systems. Typically used in determining the working parameters of heat exchangers, it can be employed to improve the heat fitting between the source of heat and the working fluids of the ORC system. To attain the parametric match, an algorithm was built enabling quick estimation of the possible heat reception by the specific working fluid. In effect, it is now possible to attain quick estimation of the upper limits of the electrical power output and the overall conversion efficiency. This paper outlines the developed algorithm and the range of its possible applications and presents the results of sample calculations. Copyright © 2013 John Wiley & Sons, Ltd.     

Application of ultrasonic wave celerity measurement for evaluation of physicochemical properties of olive oil at high pressure and various temperatures

High-pressure processing is a powerful technology for food preservation. The knowledge of foods properties in the high-pressure range is important to develop and optimize such processes by means of mathematical modeling and simulation. Ultrasonic methods are rapid, non-invasive and can be used to characterize foods like edible oils (e.g., composition, purity, and quality assessment). In this paper, they were applied for the investigation of physicochemical properties of olive oil at high pressure at different temperatures. The sound wave velocity was measured by the pulse-transmission method and the corresponding oil density was additionally determined from the monitoring of sample volume change. Measurements were conducted in the pressure range up to 600 MPa, for temperatures from 20 to 50 °C. Intermolecular free length, isothermal and adiabatic compressibility versus pressure were calculated using measured sound speed and density isotherms. Discontinuities in the measured isotherms of sound speed and density versus pressure indicate the presence of liquid-to-solid phase transitions. The kinetics of the liquid-to-solid phase transition was also investigated. The transformation times of olive oil augment with increasing temperature. This study can be broadened to other liquid foodstuffs to investigate the influence of temperature on their physicochemical properties at high pressure.     

Discrete distributions for which the regression of the first record on the second is linear

The linearity of regression of the first record on the second is examined for discrete random variables. Both ordinary and weak records are considered. The analysis involves the determination of all possible linear relationships and all possible probability distributions. Several characterizations of geometric distributions are also shown.     

Analysis of Pipes Containing Plain and Gouged Dents

Abstract: The paper discusses numerical results obtained for pipes subjected to transverse denting by a rigid indenter. Dents produced by different shapes of indenters are assessed for the amount of cross‐sectional distortion of the pipe and for propagation of this distortion along the length of the pipe. The contact area between the rigid indenter and the deformable pipe, as well as between the pipe and the rigid support is calculated for different loading configurations and for different shapes of indenters. Pipe supports considered include elastic springs, a rigid saddle and a rigid plate. In numerical work, axial cracks and gouges of different sizes have been introduced to the pipe's outer surface. Damaged pipes are then subjected to denting and results, including denting forces, distortion of the cross‐sectional area and limit loads are compared with the corresponding results obtained for non‐dented and non‐gouged geometries as well as with non‐dented but gouged cases. Finally, selected numerical results are compared to experimental data in order to demonstrate the adequacy of the adopted modelling and analysis approach.     

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life were investigated in this study. In particular, the changes in antioxidants content, antioxidative and reducing capacity, and Maillard reaction development in rye ginger cakes after long-term storage were addressed. Ginger cakes produced according to the traditional and current recipe were stored for 5 years at room temperature in a dark place. The total phenolic compounds (TPC), inositol hexaphosphate (IP6), reduced (GSH) and oxidised glutathione (GSSG) contents, antioxidant and reducing capacity and Maillard reaction products (MRPs) were determined in ginger cakes after storage and then compared to those measured after baking. After long-term storage a decrease in TPC and IP6 contents in cakes was noted. In contrast, an increase in antioxidative and reducing capacity of stored cakes was observed. Long-term storage induced formation of furosine, advanced and final Maillard reaction products and caused changes in both reduced and oxidised forms of glutathione. After long-term storage the modest changes in furosine, FAST index and browning in ginger cake formulated with dark rye flour may suggest that this product is the healthiest among others. Therefore, traditional rye ginger cakes can be considered as an example of a healthy food that is also relatively stable during long term storage as noted by the small chemical changes observed in its composition.     

The information of ambiguity

The phase space characteristics of a quantum state are best captured by the Wigner distribution. This displays transparently the diagonality information of the density matrix. The complementary function offering transparently the off-diagonal elements is captured by a function called the S-function, or the ambiguity. In carrying the maximal information about the quantum coherences it represents the uncertainties or ambiguity of the diagonal information. Mathematically this is manifested in its role as the phase space moment generating function. Formally it complements the information in the Wigner function. These formal relations provide the starting point for the present investigations. As a measure of quantum uncertainties, ambiguity may be used to define a probability measure on the off-diagonality. The mathematical and physical consistency of this view is presented in this paper. For a pure state, we find the extraordinary result that such distributions are their own Fourier transforms. The physical interpretation of this distribution as a carrier of classical signal fuzziness suggests the introduction of heuristic approximations to the observational uncertainties. We illustrate the properties and interpretation of the ambiguity function by some specific examples. We find that for smooth, ‘Gaussian-like’ distributions, the heuristic considerations provide good approximations. On the other hand, representing quantum interferences, the ambiguity serves as the most positive probe for the ultimate quantum structures which have been called sub-Planckian. They are interesting because it has been argued that such structures are physically observable.     

The Light Sword Optical Element—a New Diffraction Structure with Extended Depth of Focus

Abstract

This letter introduces a novel diffraction structure, the light sword optical element, with extended depth of focus.     

Influence of salt concentration on properties of marinated meat from fresh and frozen herring (Clupea harengus L.)

Salt concentrations of brine above 10% are still commonly used in fish marinating process. The study has showed an increasing salt concentrations affect to adversely all the properties of marinated herring meat. Increase in salt concentration from 5% to 15% resulted in significantly (P < 0.05) decrease content of water, non‐protein nitrogen and products of protein hydrolysis. Consequently, weight yield of marinated fresh herring decreased from 83% to 74%. The most palatable marinades contained 2–3% NaCl in meat only. The higher salt concentrations applied significantly (P < 0.05) worsened the taste, texture and colour of marinated herring. Texture profile analyses (TPA), free hydroxyproline content and colour analyses (L*a*b) confirmed the negative influence of high salt concentration on the marinades quality. Frozen and thawed herring tissue showed greater sensitivity to salt. Namely, marinades from frozen fish contained by 0.3 more salt (P < 0.05), and the weight yield was by 2.3–10.3 percent point lower than from the fresh herring. Meat from frozen herring when matured has significantly (P < 0.05) lower sensory value, lower content of protein hydrolysis products, free hydroxyproline and higher parameter b* value of than the fresh one.     

Antioxidative and reducing capacity,macroelements content and sensorial properties of buckwheat‐enhanced gluten‐free bread

Common buckwheat flour (BF) was used to substitute 10%, 20%, 30% and 40% of corn starch, the main component of a gluten‐free bread formula, to make buckwheat‐enhanced gluten‐free breads. The 40% BF‐enhanced gluten‐free bread showed the highest antioxidant capacity against ABTS⁺˙ and DPPH˙ radicals (4.1 and 2.5 μmol Trolox g^?1 DM, respectively) and reducing capacity measured by cyclic voltammetry (1.5 μmol Trolox g^?1 DM). The antioxidant and reducing capacity of buckwheat‐enhanced gluten‐free breads were positively correlated with their total phenolic contents (r = 0.97). The 40% BF‐enhanced gluten‐free bread showed the highest overall sensory quality (7.1 units) when compared to control gluten‐free bread (1.8 units). The linear relationship between applied increasing BF doses in gluten‐free bread formula and magnesium, phosphorus and potassium content in breads was noted. It was concluded that 40% BF‐enhanced gluten‐free bread could be developed and dedicated to those people suffering from coeliac disease.     

Mass loss determination of wheat kernels infested by granary weevil from X-ray images

Mass losses in wheat kernels infested by the granary weevil were determined using soft X-ray imaging. The mass loss strongly depended on the life stage of the pest insect. Hence, determination of the correlation between developmental stage and mass loss may help to decide management strategies and can also be used to determine time and place of infestation. The mass losses were calculated from X-ray images, taken from 20 to 66 days after infestation, using the grey scale. To compare calculated mass loss (CML) with the actual mass loss, wheat kernels were weighed. Interdependence of the mean values of the CML and weighed mass (WM) on infestation time was determined and fitted by linear and polynomial curves. During these studies kernels from the infested sample were assigned to six categories based on the CML and morphological features obtained from the X-ray images. The categories were as follows: sound, small larva, medium larva, large larva, pupae and emerged. Comparison of kernels assigned to categories based on mass with kernels classified by area of grey scale revealed that mass was more reliable in assigning grain to particular classes. The mass index decreased the number of wrongly classified kernels. The polynomial curve for mass loss can be used to give an indication of the time and place of infestation.